The present invention relates to a procedure for automatically disposing and fetching carts and a device for carrying out said procedure, for example with carts carrying goods in factory buildings or the like.
In, for example, the engineering industry it very often occurs that stock such as raw materials, unworked details and finished details are transported in large lots on carts between different stations, such as raw material stocks, intermediate stocks, working stations and finished products stocks.
In, for example, large forging plants forgings are intermediately stocked on carts. One cart at a time is taken to the desired working station, for example, a forging press and empty carts and carts with worked details are fetched or are gone after and returned with.
The transport of the carts may be done manually or with the aid of a traction truck. A solution that has been used more often uses automatic traction trucks which, for example, are directed by loops in the floor. With the aid of a well designed system of this type it is possible to automatically transport carts for the described purposes in a desired way inside a plant. In a well functioning transport system of the said type it is very important that the disposing or placement of the carts in a certain order or alignment and the fetching of carts at the different stations may be done automatically and reliably.
An automatic, intermediate stock station centrally positioned in a plant is, for example, arranged in such a way that the carts are positioned in a row next to one another with their longitudinal directions parallel to each other and their longitudinal directions at right angles to the longitudinal direction of the row of carts. During disposition the traction truck and the cart are driven at a right angle to the row of the carts and the traction truck passes through the row of carts before the placement of the cart and before it is stopped and is disconnected from the pulled cart so that the pulled cart is disposed at the desired position in the row.
However, the automatic fetching of carts disposed in this manner has associated problems. During a fetching operation, preferably, the back part of the traction truck should be brought near the front part of the disposed cart in order for a coupling to be performed by a coupling arrangement of which one part is situated on the traction truck and another part is situated on the cart. During such a coupling, the demands on precision are high because the system is automatic and the coupling together must be done with a very high reliability of operation. Further the cart after the coupling to the traction truck must be pulled out from the row of carts essentially at a right angle to the row and parallel to the other carts because the cart with its load must not come into contact with adjacent carts or the loads on those carts. The carts are disposed rather near one another as usually the smallest possible size of the disposition area is desired.
One solution would be to move the traction truck backwards to a coupling position relative to the cart to be fetched, or corresponding to the truck position at the disposition of the cart. With a loop-directed traction truck however, such a well controlled backing movement as is needed, unfortunately, is very difficult or impossible to provide.
The present invention relates to a procedure which solves the abovementioned problems and where the need for unacceptable backing movements has been eliminated.